Core 2 and newer are just excellent. Poor old AMD.
AMD's chips are just fine, but intel chips are better. However, if you're looking low-end, AMD is more value for money! Of course, I have a shiny new 6-core top-end i7 extreme...
But my laptop runs a core 2 duo released in 2008 or whatever. It's a beast. My laptop is still perfectly fast in 2013. Running linux helps, of course, but even my windows 8 install is fast enough when I feel like booting it up for some reason.
If your old computer is having trouble doing basic tasks, here's what I'd say.
- Your computer hasn't innately gotten worse. Most devices in the box work perfectly until they die, with very little degradation.
- I assume you're running windows, so:
- Defragment the hard drive; there's a windows tool to do this already installed.
- Clean your registry; use something like ccleaner.
- Uninstall any crap you don't need.
- Clean the registry again.
- Delete any files you don't need that were left over by the uninstall process.
At this point, things tend to be running smoother. But if not:
- Start your task manager, and sort the columns so you see what programs take up the most CPU cycles and the most memory.
- Are those programs you want? Do you know what they are? If you don't know, google to find out.
- Look in your startup folder. Chances are you've accumulated, like, ten+ programs there that start up and run 24/7. If you don't need them, remove them.
- After figuring out the biggest offenders and removing them, clean the registry again.
Oh, one more thing.
Get rid of your toolbars. Every single one. Right now. A lot of folks think these are a good idea. Delete with extreme prejudice, clean the registry, then check if they're actually deleted.
That tends to solve most problems... if not, you have more choices, such as re-installing windows, or asking your computer-nerd niece or nephew to clean things up for you twice a year (and paying them; if they're teenagers, at least $30, or $10/hr whichever is more, or if they're adults, double that.) If you think the price is steep, compare it against what a professional shop charges (and remember that they won't try to up-sell you or lie to you or install weird programs.)